Liquid crystal display devices (LCDs) include the transmission-type liquid crystal display device which utilizes backlight from behind the display panel as a light source for displaying, the reflection-type liquid crystal display device which utilizes reflected light of external light, and the transflective-type liquid crystal display device (reflection/transmission-type liquid crystal display device) which utilizes both reflected light of external light and backlight. The reflection-type liquid crystal display device and the transflective-type liquid crystal display device are characterized in that they have smaller power consumptions than that of the transmission-type liquid crystal display device, and their displayed images are easy to see in a bright place, and thus are suitable as display devices for mobile phones, portable electronic devices, and the like. The transflective-type liquid crystal display device has an advantage in that its screen is easier to see than that of the reflection-type liquid crystal display device, even in a dark place.
In the reflection-type liquid crystal display device or the transflective-type liquid crystal display device, in order to perform bright displaying with a wide viewing angle, it is necessary to allow incident light entering the display device to be more uniformly and efficiently reflected by the reflection surface across the entire display surface, without causing specular reflection in one direction. For this purpose, it is better if the reflection surface has moderate ruggednesses, rather than being a complete plane.
Examples of conventional reflection-type liquid crystal display devices are described in Patent Document 1 and Patent Document 2.
On a face of a liquid crystal layer of the liquid crystal display device of Patent Document 1 that faces a TFT substrate, a photosensitive resin layer, an acrylic resin layer, and a reflective layer are stacked in this order. By photolithography technique, minute dents are formed in the photosensitive resin layer, and, conforming to these dents, a non-flat reflection surface is formed on the surface of the reflective layer. According to Patent Document 1, reflected light having excellent light scattering characteristics is obtained with such a reflection surface, whereby displaying contrast is supposedly improved.
Patent Document 2 describes a method of realizing an improvement in the light scattering characteristics of a liquid crystal display device through simple processes. It states that, by polishing the glass substrate surface of a CF (color filter) substrate with polish powder to obtain a coarse face, a liquid crystal display device with excellent light scattering characteristics can be obtained. Moreover, this document also describes a method of improving light scattering characteristics by forming an insulating layer having ruggednesses on a TFT substrate and forming electrodes to function as reflectors on the insulating layer pixel, thus roughening the surface of the pixel electrode.
[Patent Document 1] Japanese Laid-Open Patent Publication No. 5-232465
[Patent Document 2] Japanese Laid-Open Patent Publication No. 8-338993